Add: string.gmatch

src/Lua/Standard/OpenLibExtensions.cs

@@ -95,6 +95,7 @@ public static class OpenLibExtensions
         DumpFunction.Instance,
         FindFunction.Instance,
         FormatFunction.Instance,
+        GMatchFunction.Instance,
         LenFunction.Instance,
         LowerFunction.Instance,
         RepFunction.Instance,

src/Lua/Standard/Text/GMatchFunction.cs

@@ -0,0 +1,55 @@
+using System.Text.RegularExpressions;
+using Lua.Internal;
+
+namespace Lua.Standard.Text;
+
+public sealed class GMatchFunction : LuaFunction
+{
+    public override string Name => "gmatch";
+    public static readonly GMatchFunction Instance = new();
+
+    protected override ValueTask<int> InvokeAsyncCore(LuaFunctionExecutionContext context, Memory<LuaValue> buffer, CancellationToken cancellationToken)
+    {
+        var s = context.GetArgument<string>(0);
+        var pattern = context.GetArgument<string>(1);
+
+        var regex = StringHelper.ToRegex(pattern);
+        buffer.Span[0] = new Iterator(regex.Matches(s));
+        return new(1);
+    }
+
+    class Iterator(MatchCollection matches) : LuaFunction
+    {
+        int i;
+
+        protected override ValueTask<int> InvokeAsyncCore(LuaFunctionExecutionContext context, Memory<LuaValue> buffer, CancellationToken cancellationToken)
+        {
+            if (matches.Count > i)
+            {
+                var match = matches[i];
+                var groups = match.Groups;
+
+                i++;
+
+                if (groups.Count == 1)
+                {
+                    buffer.Span[0] = match.Value;
+                }
+                else
+                {
+                    for (int j = 0; j < groups.Count; j++)
+                    {
+                        buffer.Span[j] = groups[j + 1].Value;
+                    }
+                }
+
+                return new(groups.Count);
+            }
+            else
+            {
+                buffer.Span[0] = LuaValue.Nil;
+                return new(1);
+            }
+        }
+    }
+}